Telephone system



` 1,578,809 H. D. cuRRlER ET AL TELEPHONE SYSTEM Filed Sept. 27, 1922 6 Sheets-Shea?l l NNN www mwN .7m/EWE' ITZIEZWUZ'UFJ'ZPP 5012751255 2022.

March `30 1926.

March 30 1926. 1,578,809

H. D. CURRIER El' AL TELEPHONE SYSTEM Fnled sept, 27, 1922 l 6 sheets-sheet 2 N l n r-f f.

R ry m g 3: a 9

March 30 1926.

1,578,809 H. D. cURRn-:R ET AL TELEPHONE SYSTEM Filed Sept. 27, 1922 G Sheets-Sheet 3 fly-@ Hz'rml? E urz-'2192" E Qfge b T E 7 @M41 March 30 1926.

H. D. CURRIER ET AL TELEPHONE SYSTEM 6 Sheets-Shea?I 4 Filed Sept.

March 30 1926. 1,578,809

H. D. cURRlER ET AL TELEPHONE SYSTEM Filed Sept. 27, 1922 6 Sheets-Sheet 5 March 3o 1926. 1,578,809

H. D. CURRIER ET AL TELEPHONE SYSTEM Filed Sept. 2'7',v 1922 6 Sheets-Sheet `6.

Patented Mar. 192:6.

. UNITED sTATEs l 1,578,809 PATENT OFFICE.

rIIIRAM n. CUREIEE, OE CHICAGO, AND GEORGE n. EATON, OE OAK PARK, ILLINOIS, AssIGNORs To KELLOGG swITCHBOARn AND SUPPLY COMPANY, or CHICAGO, ILLINOIS, A CORPORATION or ILLINOIS. g y y TELEPHONE SYSTEM.

Application filed September 27, 1922. Serial No. 590,785.

To all fwioma't may concern: v

Be it known that we, HIRAMD. CURRIER and GEORGE R. EATON, citizens of the United States of America, and residents, respectively, of Chicago and Oak Park, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Telephone Systems, of which the following is a specification.

Our invention relates to telephone systems, and ha-s to do more particularly with systems known as the magneto typein which the subscribers may be interconnected for conversational purposes, and one of the main objects of our invention is to prov1de an improved circuit arrangement of the above type.

In the telephone field large operating telephone companies are built up of a number of telephone exchanges, some of them comprising common battery equipment, and some of them comprising magneto eqmpf ment'. The outlying exchanges in the rural districts are mostly of the magneto type and are small. in size. maintaining of an operating force to operate the board, which usually consistsof one or two operators. Only a small per-l centage of the operators time is required for the proper handling of calls on a board of this size, and an object of our inventlon is the provision of an improved circuit arrangement in which the operator instead of being placed at the magneto board at a* smalbtown may be placed at a centralized control board at one of their main exchanges in a large city where she may handle the regular work in acldition to estab-A lishing connections between magneto' subscribers at the outlying magnetfo exchange, or an operator may be assigned to handle all the calls from several small` exchanges. The equipment` used for .establishing connections between the different subscribers at" the magneto exchange'islocated at the small town and comprises a plurality of switchlng instrumentalities for interconnecting the lines under the control of 'the operator at the' centralized control position located in the board at the main exchange.

One of the features of our invention is the termination of the lines of a magneto exchange in the banks of finder switches,

This necessitates the vas on a regular magneto cord;

of which one is actuated when a subscriber rings central `to select vthe calling line, and the provlsion of suitable operators answering equipment inthe form of a suit-able y switch which when actuated selects the connecting circuitpredetermined by the starting circuit when the subscriber rings central tov connect the calling subscriber with the operator at the centralized control board at the main exchange.

Another feature of 'our invention is the provision lof suitable operators answering equipment which is automatically connected to the calling line and dialing means in the loperators answering equipment for dialing the number of the called subscriber in the sameexchange, and restoring meansfor restoring the switch which automatically` functions to connect the operators answer- Iing equipment with the calling line after the operator has supervised the connection in the usual way so that the Same may beimmediately available for selecting any other call which may have been placed in the meantime.

Another feature of our invention is the provision ot an operators supervisory equipment associated with the operator at the' main exchange, and a supervisory switch associated therewith which may be stepped from one connecting circuit to 'the next,4

and those in use she may `supervise the same s supervisory provision yof a special tone associated withy the 'operators supervisory equipment which will be heard by the operator supervising Means are permitting the ringing of a A connections when a connecting circuit has parties to ring of'f so thatfthe same may be not been released due to the failure of the released'by suitable -means associated with Vthe supervisoryv equipment. l

Another feature of our invention is the provision of means wherebyV the lmagneto;00

subscribers may ring central to ground. to start-the switch apparatus to select the calling line through the agency of a grounding key at the subscribers station, or the subscribers may ring each other onthe line nietallically without disturbing the control operator atthe central office, thus -eliminating the use of any battery on the magneto line circuit. Y

Still another feature of our invention is the provision of a harmonic frequency selective circuit which\ is operated by suitable impulses to select the proper ringing frequency to ring the call bell at the call substation "that is located on a party line and is equipped with frequency ringing apparatus.

For a more complete understanding of our invention, reference may be had to the accompanying drawing in which we illustrate apparatus for interconnectin magneto subscribers` lines, and in whic Figs.

1, 2, 3, 4, 5 and 6, whenjoined as. shown in Fig. 7 illustrate a complete connection. All of the parts have been shown at normal, and the apparatus illustrated in Figs. 1, 2, 4 and 5 is locate'dfat the magneto exchange at a distant point from the mam central office. The apparatus in Fig. 3 .illustrates the operators control equipment which is located at the centralized controlr otlice at the main exchange. toll line circuit to be used in connection with the other circuits if necessary.

Referring -now more in general to our invention, and for the purpose of illustrating and describing the same, we show a system whose ultimate capacity is 46 lines, which lines are single party or party lines equipped with straight line or code ring1ng,'

andparty lines which are equipped with harmonic ringing. In a system of this type inl which the capacity is 46 lines, seven finder switches FS, through which these 46 lines are multipled, and seven connector switches CS, through which said forty-,six lines are multipled, are provided, and these switches provide seven connecting circuits CC, each comprising a pair of switches FS and CS which are sufficient to handle the traflic between said subscribers of the exchange. The number of switches just given is used as an arbitrary measure, as the number of switches may be increased or decreased depending upon the traiiic. 'f

An answering switch AS common to the seven connecting circuits automatically selects the predetermined connecting circuit as selected by the finder switch FS, and auto` matically connects the operators equipment OA and OE located at the centralized control board atfthe main oflice with the calling line at the magneto exchange, and

Y through the medium of a suitable' impulse transmitting device actuates the connector switch CS to select the contacts of the called line. A ringing frequency selective circuit FR associated with the connector switch CS operated byimpulses from the impulse device located at the central control ofHce is adapted to select the proper generator frequency tb ring the call bell cfa called Fig. 6 is aV subscriber. We also provide asupervising switch SS common to all the connecting circuits which may be actuated by suitable means associated with the operators supervisory equipment OE to step the wipers of the switch. SSfrom one set of contacts to the next to which the connecting circuits are connected for the purpose of supervising connections as is the case in a magneto exchange. l.

Referring now more in detail to our invention as illustrated, in Fig.-1, to the left of the drawing, -we show a magneto substationA which is one of a plurality located at the magneto exchange M and is provided with a grounding push button GB which when actuated and the hand genera tor operated causesv a finder switch FS to operate to select the contacts of the calling line. The substation A terminatesl at the exchange M into a line circuit L comprising the usual line relay LR and a secondary line relay LR and a cut off relay CO. The line circuits L of the lines are multiply connected to the finder switches FS, whereby any one of the switches FS may seize the calling line terminals, as will be more. fully hereinafter described. The finder switch FS may be of any desired construction and is provided with a spring restored shaft which carries wipers 11, 12, 13 and 14 and with four sets of'iifty contacts 15, 16, 17 and 18, to which contacts the lines of the subscribers of the exchange M are multipled.

A rotary magnet RM is provided for rotating the switch shaft and its wipers 11, 12, 13 and 14 by means of a suitable ratchet and pawl mechanism. A. release magnet RE is also provided which when actuated is adapted Ato bring about the restoration of the switch shaft and its associated wipers 11, 12, 13 and 14. -A common starting con ducto-r ST is provided and is common to the subscribers lines which lead to the group of switches FS. A bridging relay BG is provided which energizes when the calling line is seized by the switch FS to shunt the rotary magnet RM to prevent further advancement of the wipers 11, 12, 13 and 14, and a switching relay SW is provided which energizes upon the actuation of the relay BG to extend the starting conductor ST llf) through to the next finder switch FS of the RM for rotating the switch sha-ft and its Oli' normal contacts '64,",65, 66 and 67 which lead to the linder I switches FS. A release-magnet RE for releasing the switch AS is also provided, and v a bridging relay BGH/,is provided which energizes when the predetermined connecting circuit CC now connectedto the calling line is seized by the answering switch AS to shunt the rotary magnet RM to prevent further advancement of the wipers 60, 61, 62 and 63. Relay BG upon energization extends the calling line over conductors 97 and 118 to the operators centralized control equipment OA4 and OE `at the main exchange asillustrated in Figq 3. The operators equipment at the main exchange N for interconnecting the subscribers at the exchange M comprises equipment which weyL will term operators answering equipment OA, and which comprises a call lamp CLl which is lighted when the operator is connected to the calling line to indicateto her that a call is awaiting her attenti-cn. A listening key LK is provided which when actuated connects her operators set O to the cnductors97` and 118 so as to place her in communication with the calling line. A

dialing key DK is also provide-:l which when actuated connects the calling dial CD so that thesalne may be operated 'to send the requisite number of impulses to' select the called line. A ringing key RK is also provided for-ringing the called for subscriber. t

' The connector switch CS to which the lines7 are multiply lconnected is of a construction similar to that of switches and AS and comprises a shaft carryin wipers 159, 160- and 161 which are adap tobe stepped into engagement# with the contacts 162, 163 and 164; through the medium` of a rotary magnet RM2. A release magnet R122 is also provided which when actuated re` leases the switch wipersl 159, 160 and 161 and allows them to restore to normal. The connector switch is of the fifty point rotary type and we leave the tenscontacts of the bank contacts blank, that is, the tenth, twen-` tieth, thirtieth and fortieth set of contacts are 'ot connected tothe subscribers 'lines but are` left blank or on open` circuit. vAssuming-that a subscriber is calling a subscriber whose line is connected tothe twentyifth set of contacts, the operator will operate her calling device CD to send ten-impulses which `will operate the connector switch CS to cause the wipers to enga-ge the v tenth set of contacts in the `bank which are blank. The operator willnow actuate the calling device to send the second group of tenV impulses which will step the wipers of the connectorl into engagementrwith .the twentieth set of contacts of the bank which are also blank and the final live impulses will step the wipers of the connector switch ,soo

necting circuit tothe next.

into .engagement with the twenty-lifth set of contacts which are the'contactsof theI wanted line. Now, iftthe tenth and-twentieth sets of contacts hadv a subscribers line connected thereto, and shouldthe said line connected `thereto be in conversational circuit, the're would be interference with the connection when' the wipers engaged ,the tenth and twentieth 'set of contacts, but by leaving the tenth, twentieth, thirtieth and orteth set of contacts blank, the wipers will always engage blank contacts andl prevent interference with existing connections and thus provide for capacity' of forty-six lines. Ainging frequency selecting circuit FR is also'associated with-the switch CS and .comprises a group of ring frequency selec--1 tive relays RFS, RF S RFS2 and RFS3 'one of which is associated with each of the. frequencygenerators G, G', Gr2 and G3.' The .85 relays RFS, RFS', RFS2 and RFS3 are 4operated by impulses from the calling device CD of the operators centralized equipment at the main exchange depending upon the frequency selected, and through the agency of the ringing-key RK oi' the operators equipment OA the called subscriber may be signaled. .v j

To the right of the drawing we show a called substation B similar to the calling substation A which terminates-,at the exchange M in a line-circuit L similar to thatof L\ of Fig.1, and comprises `line relays LR2 and LR? and cut off relay CO.`

In Fig. 5 we illustrate a supervisory 100 switch SS` common to all the connecting circuits CCof the exchange M and through the medium of the operators supervisory v equipment OE at the main exchange the switch SS may be stepped from mieten- The switch is similar in construction to that'-of FS of Fig. 1, and comprises Va rotary magnet RM3 which steps the wipers 281, 282,'283and 284 from one set of contacts 285, 286, 28.7

land'288 to the next to supervise connections.

A releasemagnet'RE3 is also provided for releasing the switch -SS to permit the switch Wipers to restore. The supervisory equiplment OE at the centralized position or' the115 main lexchange comprises a listening key LK which when actuated connects the operators set O to the connecting circuits when she is supervising. A stepping key GSK which' when actuated by the operator steps the 12u wipers 281, 282, 283and 284 from one set of contacts 285, 286, 287 and288 which pare associated with the connectingq circuits.l A ringing key RK isalso provided which may vhe operated tore-ringa called subscriber who has not as yet answered when the operator is supervising and has found` such a condition,

all .of which will be more fully hereinafter described. '4 A In Fig. 6 we illustrate a toll linecircuit 13.0

release of'the switch Wipers.l

which terminates at. the centralized control board at the main-exchange N Where a truck jack TJ, the disconnect lamp DL, the cut oft relay GO2 and the relay 387 which controls the lighting of the disconnect lamp DL are all located. dial connecting key DK- and a calling device OD are also associated withand located at the main exchange M. The toll linecircuit comprovided which assume their alternate po-` sition upon' the irst step of thev wipers ofi' normal. A release magnet RE4 is also provided whi'ch when energized permits the The switch TCS is of a construction similar to that of switch FS of Fig. 1, and is of any suitable non-numerical type. A frequency selecting circuit FR is also associated with the switch TCS which is'similar to the frequency selecting circuit FR associated -with the connector switch CSY of Fig. 4.

Having described in general the apparatus comprising the circuits of our invention, we will nowV describe in detail the operation of the same.. y f

Assuming that the subscriber at thes-ubstation A located at the exchange M initiates a call, he depresses the grounding key GB and operates the hand generator at the substation. The iiow of current from the operated hand generator causes the line relay LR to operate, and the closing of its alternate contact 1 establishes an energizing circuit for the secondary line relay LR from battery through the winding of relay LR', conductor, normal contact 4, of cut off relay CO to ground at alternate contact 1 of relay LRL- The closing of alternate contact 5 lof relay LR places ground on the starting conductor ST and establishes an energizing circuit for `the rotary magnet RM of the finder switch FS, traced from ground at alternate con/tact 5-of relay LR', starting conductor ST, normal contact 6 of switching relay SW, conductor 7, normal contact 8 of o-normalcontacts ON, conductor 9, normal contact 10` of magnet RM through the winding` of magnet RM to battery. The rotary magnet'RM is energized and de-energizedronce over this circuit to step the wipers 11, 12, 13 and 14 of the finder switch into engagement with the first set of contacts 15,16, 17 and 18. The circuit for rotary magnet RM is opened upon the first step of the wipers 11, 12, 13 and 14 o normal, due to the opening rsasgo y of normal Contact 8 of onormal contacts ON which assume their alternate position upon the first step of the wipers. A substitute energizing circuit is-however established for the rotary magnet RM which may now be traced from batteny through the windingv of magnet RM, its contact 10,v

conductor 9, alternate contact 8 of off-normal contacts ON, conductor 19, normal contact 20 ofrela SW to ground at normal contact 21 of brldging relay BG. d The rotary magnet RM is alternately energized and deenergized over this circuit to step the wipers 11, 12, 13 and 14rom one set of contacts 15, .16, 17 and 18 to the next in search of the contacts of the calling line.

The wipers 11, 12, 13 and 14 when stepped into engagement with the contacts 15, 16, 17 and 18 of the calling line cease further travel, and the instant wiper 12 engages Contact 16 of the calling line, an energizing circuit for bridging yrelay BG is established traced from battery 22 over conductor 23, winding 24 of relay BG, conductor 25, normal contact 26 of relay SW, conductor 27, wiper 12, contact 1X6, conductor 28, to ground at alternate contact 29 of relay L-Rf The instant wiper 12 engages grounded contact 16, the circuit just traced closes a low resistance path through the lWinding of relay BG to shunt rotary magnet RM, preventing further operations of the same, and relay BG upon energization opens the circuit of magnet RM at its normal contact 21.

Relay BG upon energization establishes an energizing circuit for cut off relay CO of the line circuit L and the switching relay SW )of the finder switch FS traced from ground through the winding of relay CO, conductor 30, contact 15, yWiper 11, conductor 31, alternate contact 32 of relayl BG, conductor 33 to battery through the winding 34 of relay SW. The rel'aysCO and SW are energized over this circuit and the closing of alternate contact/35 of relay SW establishes a locking circuitl for itself traced from battery through its upper Winding 36, its, alternate contact 35, conductor 37 to ground at alternate ,contact 38 of off normal contact ON, The closing of alternate contact'6 of relay SW now extends the common starting conductor ST through said alternate contact 6 to the starting` Wire ST which leads to the next finder switch FS ot the group, so that should another subscriber initiate a call, the call will be extended to the nextswitch of the group. A busy potential is also placed upon the private contact 162 of the connector switch associated W ith the'calling line to busy the same against incoming calls. A

The closing of alternate contact 39 of relay Sl/V establishes a locking circuit for relay BG traced from battery 22, conductor 23, winding 24 of relay BG, `conductor 25,

alternate contact 39 of relay SW, conductor .40, winding 41 of relay BG, conductor 42, to ground atnormal contact 43 of the release controly relayI REC. The relay BG- lupcnenergizing closes its alternate contact 21, establishing an energizing circuit for the The closing of alternate contact 50 of relay AN establishes an energizing circuit of the rotary magnet RM' of the answering switch AS, traced from-battery through the wmdi ing of magnet RM', its normalcontact 51,'

conductor`52, normal contact 53 oi oil-normal contacts ON? of answering switch AS, conductor 54, normal contact55 of switching relay SW', conductor 56, normal contact 57 of tone connecting relay TRE of the supervisory switch` SS, conductor 59, to ground at alternate contact 50 of relay AN. The magnet RM' of Athe answering switch AS is energized and de-energized one-cover this circuit; to step the wipers 60, 61, 62 and 63 into engagement \with the firstset of contacts 64, 65,v 66 and 67. The movement .of thewipers 60, 61, 62 and 63 one step permits the off-normal contacts ON2 toy assume their alternate position and the openingof normal contact 53 of off-normal contacts ON2 opens the initial energizing circuit of the magnet RM', but a substitute energizing circuit for the magnet RM'is established which may be traced from battery through the windin` of magnet RM', its normal contact 51, con uctor 52, alternate contact 53 of off-normal contacts ONZ, conductor 68, normal Contact 69 of relay SW', conductor 70, Ito ground at normal contact 7l of bridging relay BG'..

The magnet -RM' is alternately energized and de-energized over this circuit due to the interruption of its normal contact 51 to step the wipers 60, 61; 62 and 63v from one contact set 64,'65, 66 and 67 to the nextin .Y search of the finder switch FS that selected the calling line. When the wiper 60 of the answering switch AS engages the contact 64 which leads to the line finder FS, an enere gizing circuit is established for the relay BG', traced from battery 72, over conductor 73, through the windig-74 of relay BG',g conductor 75, normal contact J7 6 of relay SW', conductor 77, wiper 60, contact 64, conductor 7 8 tol ground' at alternate contact 79 ot relay AN. The circuit just described closes` a low resistance path through the winding 74 of relay BG' and shunts the magnet RM' to prevent further actuations of the same, and the wipers 60, 61, 62 and 63 remain in engagement with the selected contacts 64, 65, 66 and 67 which lead to the con- -TI. Relay CLC is energize necting circuit CC associated with the finder switch YFS that selected the calling line. The relay BG' upon energizationy closes its a1- ternate contact 71, establishing 'an energizi ing circuit for switching relay SW', traced from battery through windin ofrelay SW', conductor 81, to roun at alternate contact 71 of relay B The relay SW' energizing, its alternate contact 82 is closed to establish a locking circuit for itself, traced frombattery through its winding 83, its al-A v closing of alternate contacts .93 and 94 of relay BG establishes an energizing circuit for the call lamp control relayOLC of the operators answering equipment OA located at a centralized osition at the main exchange N, traced rom battery, through the winding of relay SE, conductors 95 and 96,

alternate contact 94 of relay BG', conductor 97, contact 98 of the connector release key CRK of the operators supervisory equipment OE, contact 99 of the ringing key RK of the operators supervisory equipment OE normal contact 100 of the operators.` Superf visory switch stepping key GSK, normal contact 101, of the listening key LK, conductor 102, normal contact 103 of the calling switch release key'CSW, normal contact 104 of relay 105, conductor 106, normal contact 107V of the listening key LK of the operators answering equipment OA, conductor 108, through the winding oit Irelay CLC, conductor 109, normal contact 110 of listening key LK', conductor 111,`normal contact 112 of key CSW, conductor 113, normalcontact 114 of thelistening key LK, normal contact 115 of-steppng` key GSK, normal contact 116 of key K, normal contact 117 of key CRK, conductor 118, alternate contact 93 of relay BG', conductor 119 and 120 to ground through thefwindin of ti relay over t is circuit, but due to their high resistance relays SE and TI do not energize, and the relay OLO, upon energization, closes its alternate contact `122, establishing a circuit for the operators call lamp CL, traced from battery through the call lamp CL, conductor 123- tralized position at the nain exchange N is lighted and signals the operator, noti ing her that a call is awaiting her attention rom a subscriber at the magneto exchange M.

lao g The operator now actuates herlistening key 1` wiper 62, contact 66, conductor 127 to lthe terminal a of the repeating coil RC.- The l other lead from the operators set O eX- tends from alternate contact 107 of the listening key LK over conductor 106, contact 104 of relay 105, normal contact 103 of key CSW, conductor 102, normal contacts 101` 100, 99 and 98 of keys LK, CSK and RK and CRK, conductor 97, alternate contact 94 of relay BG', conductor 96, normal.con tact 128 of-relay 125, conductor 129, wiper 63, contact 67, conductor 130, to the terminal b of the repeating coil RC. The listening key LK', when actuated, closes its7 alternate contact u132, establishing anv energizing circuit for the relay 133, traced from battery, through the winding of relay 133, conductor 141, to ground at alternate contact 132 of the key LK'. The listening key LK when actuated also interrupts the circuit of relay CLC, Adue to the opening of its normal,con tacts 107 and 110, vand relay CLC de-energizes, opening its alternate contact 122, ef :facing the lamp CL. The operator having been connected to the calling hne at exchange .M now inquires the wants of the calling subscriber, and assuming that the called subscribers number is 25, the operator actuates herdialing key DK and actuates her calling device CD to send twenty-five impulses, and as before de:l scribed, every tenth set of contacts of the connector switch CS is on open circuit, and to .extend the calling line to the called line, `the operator' will send two series of ten impulses each, and then send five 'impulses which will bring the wipers of connector` switch CS into engagement with contacts of the wanted line. The operator now yadvances the calling device CD to send the first` set of ten impulses, and upon the-movement of the calling deviceoi-normal, an energizing circuit is established for relay TI, traced from. battery 210,' conductor 134, closed impulse spring contacts 135 and 136,

closed shuntl spring 137, alternate contacts'l 138 and 139 of the dial key DK, conductors 140 and 111, normal contact 112 of key CSW, conductor 113, contacts 114, 115, 116

and'117, conductor 118, alternate contact 93- of relay BG', conductors 119 and 120, to

ground through the winding otrelay TI.

Relay TI upon energization closes its alter nate contact 142festablishing an energizing circuit forthe slow-acting relay SL and rowhich circuit may be traced from ground at A alternate contact 142 of relay TI, `conductor 143, normalcontact 144 of relay SE, conductor 145, wiper 61,contact 65, conductors 147 and 147', normal contact 148 of ringing control relay RCO, conductor 149 to the junction 150 and the circuit dividing and passing through the relay RR to battery and through the relay SL to battery.

The closing of alternate contact 142 of relay TI also establishes an energizing circuit -for the relay 125 of the answering switch AS traced from battery through `the winding of relay 125, conductor 145,*normal contact 144 of relay SE, to ground at alternate contact 142 of relay TI. Relay'125 is energ'zed, and due to its slow to release construct on it remains energized during the rapid interruptions of contact 142 of relay TI. The opening of normal contacts 124 and 128 of relay 125 disconnects/'the finder switch vFS conductors to prevent the calling subscriber from hearing the line interruptions caused by the impulses transmitted to actuate the connector switch CS. Vhen the operator releases the calling device CD, the

impulse springs 135 and 136 are opened and closed ten times, interrupting the circuit of relay TI ten times and each de-energization of relay TI brings about the interruption of the circuit of the rotary relay RR of the connector switch CS, and consequently rotary relay RR is energized/and de-energized ten times, but relay SL of the connector CS yhowever remains energized during the rapid interruptions of contact 142 due to its slow to release const uction\.-` Relay RR is thus energized and (le-energized ten' times, and upon each 'closure of normal contact 151 of relay RR an energizing circuit is established for the rotary magnet RM2, traced froml battery, through the magnet RM2, conductor 152, normal contact 153 of release relay REL, conductor 154, normal contact 155 'of connector test-relay CTR, vconductor 156, normal contact 151'of relay RR, conductor 157, to grounduat, alternate contact 158 of relay SL. Rotary magnet RM2 is thus energized and de-energized ten times to step the wipers 159, 160 and 161 into engagement l.

ywiththe tenth set of' contacts 162, 163vand ids 164, which are blank.v The oii normal con,

tacts ON of the connector switch CS assume their alternate position upon'the first step of the switch wipers off normal, and the opening of normal contact 46 ofsaid cti' normal contacts ON' opens the-energizing circuit of relay AN of the finder switch FS. The operator `again actuates the calling de` `vice CD `to Isend the second-set of ten impulses to operate relays TI, RRA and SL and magnet RM2 Las just described, and again actuates the calling device CD to send the final five impulses which operate the same relays and magnets of the vanswering and connectorI switches AS and CS in a similar manner as just described to place theiwipers 159, 160 and 161 of the connector CS into engagement with the twenty-fifth set of contacts 162, 163 and 164, which are the 'contacts ofthe wanted line of the called subscriber B. After the last impulse is sent lrelay TI restores and permits relays RR and SL oftheconnect-or CS to restore, and if the called line is busy eitheras a called or calling line,

the operator as well as the calling subscriber Will receive a special tone notifying them of the busy condition of the called line, as will be more fully hereinafter described.

Assuming that the called line is idle, the private contact 162 which is engaged by the private Wiper 159 is a't a ground potential CTR,rconductor 176, Wiper 159 to grounded contact 162. The relay TCR is momentarily operated but this operation is only incidental as relay CTR isv energized and the opening of its normal contact 177 opens the circuit of relay TCR. Relay CTR energizes over this circuit and the closure of its alternate contacts 178 and 179 extends the talk-A ing conductors to the called linie.

Assuming that the called subscriber B is on a party line hand said line `is equipped for harmonic ringing, the next function that the operator performs is the actuation of the calling device CD to select the proper ringing generator frequency to ring the call bell at the called subscribers substation B. Assuming that `it is the generator Gr2 which is of, the proper frequency to vring the bell at j the called substation B; the operator lnow actuates her calling device CD to send lthree impulses of current, which three impulses will energize and cle-energize the relay TI of the answering switch AS `three times, and

the relav TI will in turn again affect relays RR and SL of the connector-CS as .before described. The relay SL upon energization Will open the initial energizing circuitof relay CTR, but the closure of alternate contact 177 ofrelay 'CTR establishes a locking circuit for said relay CTR, traced from battery through the winding of relay CTR, conductor 171, normal contact 172 ofrelay REL., conductor 173, alternate contact 177 to the grounded'contact 162. The first deenergizaticn of relay RR will establish an energizing circuit for ringing frequency selective relay RFS of the frequency ringing selection circuit FR associated with the connector CS, traced from ground at alternate contact 158 of relay SL, conductor 157, nor- 7') mal contact 151 of relay RR, conductor 156, alternate Contact 155, of relay CTR, ,conductor 182, normal contact 183 of relay 180, conductor 184, normal contact 185 of relay RFS3, conductor 187, normal Contact 188 of 75 relay RFSZ, conductor 190, normal contact 191 vof relay RFS', conductor 193, normal contact 194 of relay RFS, conductor 195,- to

battery through the winding of relay RFS.

Relay RFS upon `energization opens its nor` 80 mal contact 194, opening its initial energizinoP circuit, but due to the closing ofits alterxate contact 196 a vlocking circuit is established for itself, traced from battery,

through its -winding, its alternate contact S5 196, conductor 197, normal contact 198v of relay RF S', conductor 199,A normal contact 200, of relay RFS2, conductor 201, normal contact 202 of relay RFSS, conductorv203, to

ground at alternate Contact 204 of relay 90 CTR. Relay 180 is 'also energized to bat# tery, overconductors 182 and 186, to openA its normal contact- 183 for purposes as will presently be described. The second impulse will traverse the same path just described 95 up to contact 194 of relay RFS, but now passes through alternate contactl 194 to battery, through the Winding of relay RFS.

Relay RFS uponJenergization closes its alternate contact 198, establishing a locking lo.

circuit for itself, traced from battery through its Winding, its alternate Contact 198, to ground 't alternate contact 204 of relayiCTR over the previously described path. The opening of normal contact 198 of relay 1 RF S. opens lthe locking circuit of relay RFS, which now restores. The third ringing selection impulse non;1 passes over the previously described path and passes through alternate. contact 191 to battery through l relay RFSZ, and the closing of its alter-- nate contact 200 .establishes a locking circuit for itself to ground at alternate contact 204 of relay CTR. Relay RFS2 upon energization opens its normal Contact 200,l opening the locking circuit, of relay RF S, which relay now restores. Relay 180 is also 'energized as described, and upon the firstv impulse of v`current from the calling device CD relay 180 and relay RFS of the ringing n.'

lll

l instant relays 180 and URFS are energized l",

and contact 194 of relay RFS is closed, the contact. 183 of relay 180 is changed thus preventing the impulse of current that-operated relay RFS from operating a second rei: lay RFS. -Relay RFS2 remains energized m VSL and RR of the connector switch CS restore, and the'closure of normal contact 15.8 of relay SL establishes an energizing circuit for relay RCO traced from battery, through its lower winding, conductor 207, alternate contact 205 of relay RFSZ, conductor 208, to ground at normal contact 158 of 'relay SL, and the relay ROO upon energization closes its alternate contact 209 to establish a locking circuit for itself, traced from battery, through its upper winding, alternate contact 209, conductor 210 to ground at alternate contact 204 of relay CTR. The operator having finished dialing, now restores her dialing key DK Vand actuates her ringing key RK -o'f her answering equipment OA, again connecting battery over conductor 134 through alternate contacts 212 and 213 ofthe ringing key RK', and overconductor 113 to ground through the winding of relay TI. Relay TI energizing, its alternate cgntact 142 is closed, establishing an energizing circuit for ringing Icurrent connecting relay ROC traced from battery through the winding of relay. RCC, conductor 215, alternate contact 148 of relay ROO to Aground at alternate contact 142 of relay TI. Relay RCC upon energization closes its alternate contact 216 to connect ringing current tothe called line, traced from the ungrounded pole of the selected ringing frequency generator GL', alternate contact 217 o'f relay RFS2, conductor 218, normal Contact 219 of relay RFSS, conductor 220, alternate contact 216 of relay RCC, alternate contact 178 of relay CTR, wiper 160, contact 163, through the call bell and condenser atthe called substation B, back through contact 164, wiper 161,

,alternate contact 179 of relay CTR, to

ground at alternate` contact 221 of relay RCC. Each timethe opertor wishes to actuate the. call bell at the called substation B, the ringing key RK' is actuated to operate `the relay ROG to connect ringing currentfrom lgenerator G2 to the called line. The subscriber at the called substation, in response to his call signal, removes his receiver and converses with the calling subscriber over the heavily marked conductors and through the repeating coil RO. Y

The operator having her listening key LK closed to connect her operators set O knows when the calling subscriber at the substation A and the called subscriber at the substation B are in conversational circuit, and when they are she restores her listening key LK'. The opening of alternate contact 132 of the listening key LK' opens the energizing circuit for relay 133, but due to its slow to release construction, its alternate contact 230 is held momentarily closed, thus establishing an energizing circuit for the relay 105 of the answering operators equipment OA and relay SE of the answering switch AS, traced from battery through the winding of relay SE, conductors 'and 96, alternate contact 94 of'relay BG', conductor 97, contacts 98, 99, and 101 of keys CRK, RK, CSK4 and LK, conductor 102, normal. contact 103, normal cont-act- 104 of relay 105, conductor 106, normal contact 107 of key LK', conductor 108, alternate contact 230 of relay 133, conductor 231 -to ground through the winding of relay 105. Relay SE upon energization opens its normal Contact 91 to open the energizing circuit of relay BG which restores and the closing of normal contact 71 of relay BG' vestablishes an energizingcircuit for the release magnet RE', traced from battery through the winding of magnet RE', conductor 232, alternate contact 69 of relay SW', conductor70 to ground at normal contact 71 of relay BG'.- The release magnet RE upon energization withdraws the retaining pawl andthe wipers 60, 61, 62 and 63 now restore, and when reaching their normallposition, oflnormal contacts ON2 are moved back to their normal position, and the opening of alternate contact 85 opens the circuit of relay SW', which relay restores and opens the energizing circuit of magnet RE', which now restores. The answering switch AS and its associated apparatus is now in its normal position, and

may again be used for establishing anotherY connection with a calling line. Should another call have been initiated during the time that the operator was setting up the connection just described another finder 1 switch of the group would have selected the calling line, and the operation of the relay AN of the iinder switclr would place a ground upon the common conductor 59 and the answering switch AS upon restoration would again be started to select the finder switch and'calling line so as to extend the line to the opera-tor in a manner just described.

After the subscribers have finish-ed conversation, they replace their receivers upon their respective switchhooks, and assuming the subscriber at the substation A is the first to disconnect,hedepresses his grounding but-` ton GB andactuates the hand generator and lay 240, and the said relay upon energizap tion closes its alternate contact 241, establishing an energizing circuit for relay REO, traced 'from battery through the lower winding of relay REC, conductor 243, alternate contact 241 of relay 240, conductor 244 tok ground at no rmal contact 50' of relay AN. Relay REC 1s energized over this circuit due to the closure of alternate contact 241 .tweeen of relay 240 during the time that current from generator at substation A is passing through its winding. Relay REC upon energization opens 1ts lnormal contact 43, opening the energizinof circuit of relay BG,

'but during the timetliat relay 240 is held energized relay BG remains energized l,from ground at normal contact 50 of relay AN, conductor 244, alternate Contact 241 of relay pleted for relay LR', to place ground on the 240, conductor 243, alternate contact 43 tof` relay REC, conductor'42 and' over the previously described path to battery 22. During the time relay 240 is energized, relay REC is locked' up from battery through its upper winding, its alternate contact 48, conductor 49, to ground at alternate contact 21 of relay- BG. When relay 240 restores relay BG is de-energized due tol the opening of alternate contact 241 of relay 240 and Aopening of normal contact 43 of relay REC, and

l the opening of alternate coltact 21 ofthe resubstation to restore.

stored relay BG opens one of the locking cir-4 cuits of relay REC, but a second locking circuit is closed for relay REC through its alternate contact 245 over conductor 246 to ground at alternate contact 247 of olf-normal contacts ON of the connector switch CS. The closing of normal contact 21 of relay BGestablislies an energizingcircuit for/the release magnet RE of the finder switch FS traced from battery through the winding of magnet RE, conductor 250, alternate contact 20 of relay SW, conductor 251 to ground at normal contact 21 of relay BG. The release magnet RE withdraws the retaining pawls,

allowing the wipers- 11, 12, 13 and 14 to restore and when the wipers reach theirnormail position, oit-normal contacts ON assume their normal position, and the opening of normal contact 38 opens the locking circuit of r'elay SW, which restores, and the opening of'its alternatelcontact 20 opens the circuit of release magnet REQ Relay BG restoring, its alternate contact 32 is opened, allowing relay GO of the line circuit of the calling The circuit just traced through the lower winding 41 of the relay BG to hold the said relay BG ener: gized-so that in the event that the subscriber at tlie substation A actuates the hand generator thereat to send a prolonged disconnect signal, the relay 240 remains-energized during this time and holds the relay REC energized, and the ground from normal contact extends through the alternate contact 43, through thel lower winding of relay BG to hold the same energized during this time. If this contact 43 was not provided so as t o hold the relay BG energized, .the instant:` relay REC energized ground -wouldl beremoved from the lower winding'of relay BG at normal contact 43 and permit relay BG to de-energize, and close an energizing circuit for the release magnet RE and the switch. would restore and permit the cut oli comlnon starting conductor and bring about a false start of the finder switch FS. The relay BG in restoring closes its norrnal'conY tact 252 andas relay REC is locked upto ground over a circuit as before described, an energizing circuit for relay REL of the connector switch CS isestablished, traced from battery through the lower winding of relay REL, conductor 255, alternate contact 253 of relay REC, conductor 256 to ground at normal contact 252 of relay BG.' The relay REL upon energization closes its alterT nate contact 257, closing a locking circuit for itself, traced from battery, through its upper winding, its alternate contact 257, to ground at alternate contact 247 of oil-normal contacts ON ofthe connector switch CS. The closure of alternate contact 260 of relay REL establishes an energizing circuit for the lrelease magnet RE2 of the connector switch CS from battery through the winding of magnet RE2 to groundv at alternate contact 260 of-relay REL. *The opening of normal contact 172 of relay REL opens the energizing circuit of relay CTR, and the relay CTR- upon de-energization o ens its alternate contact 204, opening the ocking circuitof relay- RFS2 of the relay frequency ringing equipment FR, and the relay RFS2 e-energizing thel ringing` selection equipD ment FR `is restored to normal. The open ing of alternate contact 204 also locking circuit of relay ROO which relay restores.y Release magnet RE2 energizing `withdraws the retaining pawl and permits the wipers 159e-160 and 161 to restore, and When reaching normal the off-normal contacts ON assume'their normal position and 4the opening of alternate contact 247 4of off- -normal contacts ON opens the circuit of relay REC of the line finder switch FS and relay RC() of the connector switch CS. The apparatuswhich was/used in establishing aconnection between the calling subscriber at `the hand generatorat the substation for disconnection, -the current therefrom will operate the connector switch release lrelay 265 and the relay, upon energization, will cloe its alternate contact 266, which closes a circuit for the relay REC ofthe finder switch d subscriberA at opens the l lIl() FS and the disconnection ofthe apparatus of finder switch FSL and` connector switch GS from this point on is the-same as just.-

described, and a 'further description is not thought necessary.

Assumin now that the line of the calledfor subscri r is busy, the operation ot the apparatus for establishing the connection from the calling line A to the called line B is the same up to and including the engagement of the wipers 159., 160`and l1^61-with the contacts 162, 163 and 164 of. the called,4

line, andbefore theoperator has dialed for theproper ringing frequency. The line being busy, there will be a busy potential on the bank contact 162 Aof the .called line, said battery also extending ,to ground through.

the cut-oil' relay G'O'. When thel test wiper 159 engages private busy .contact 162,'.test relay'GTR will not energize `due to its high resistance and due to the potential on conthe winding of relay TGR, normal contact- U 177 of relay GTR, conductor 176, wiper 159,

-nect the busydtone BT in circuit with` theV calling subscriber at substationA tovnotify the subscriber thereat ofthe busy condition 36 of the line. The busy tone is also transmitted to the operator to also indicate to her the busy condition of the called line. The circuit for relay TGR extendsfrom battery through contact 162 to ground through the cut-oi' rela1 GO' of the line circuit L of the called line. The closing of alternate contact 267 of relay TGR connects the busy tone BT to the tip conductorV back tothe calling subscriber A and to the operator. The calling subscrib- `er receiving the4 busy signal now Ireplaces his receiver and operates the hand generator to operate relay 240 and said relay energizin closes its alternate contact 241 to close `the re easecircuit of the Iinder switch FS and connector switch GS to release the switches asi previously described, The Voperator receiving the busy signal now restores her listening key LK' to close the releasejcircuit of the answering switchAS and the switch restores in .a manner already described.

The s 'stem of our invention is also'providedwith'means whereby the operator may supervise the connections 'after they lhave.

beenl established `by connecting her operators i set thereto to permit her to listen in and seeto it that all connections have been properly established and that the switches use'df in establishing connections have been re' leased, and if the subscribers have failed to release the switches v after the termination of conversation she may actuate means to re- Ilease the switches, all of whichwill now be ull described in detail,

S ouldA the operator at thecentralized conlniv/esos)l trol board at the main exchange wish to supervise the connecting circuits GG as to their condition, she will `actuatethe listening key LK of her operatorls supervisory equipment OE, and the closin V of alternate contacts 101 and 114 of the tolistening key W1 (3.0111160l e 0 ral OFS Se OVBI" LK 11 t th pe t to conductors 97 [and 118 to normal contacts 9 3 and 94 of the bridging relay BG' of the answerin switch AS, and through the medium of t e supervisory switch she may now connect her operators set to any of the connecting circuits GG so that 'she maylisten in andl supervise. The answering switch AS has been restored to normal after the operatorhas extended the call to the called substation allowing relay BG to restore to close its normal contacts 93 and 94, Vas before described.

Having actuated the listening key LK 4the operator now actuates the key GSK of lier supervisory equipment OE, and upon the actuation of the said key its alternate contact 115 is grounded establishing an energizing circuit for the interrupter lrelay IR ofthe supervisory switch SS, ltraced from battery through the winding of relay IR, conductors 270 and 27-1,.normal contact 93 of the relay BG', conductor 118, normal contact 117 of the circuit controlling release key GRK, normal contact 116 of the ringing key RK to ground at'alternate contact 115 ofl the key GSK. The relay IR upon energization closes its'alternate contact 272nes tablishing an energizing circuit. for the slow-'acting relay SL', and the ,'rotafry relay `RR' of the supervisory switch SS, the circuit of relay SL' being traced from bat- Y. i

tery through the winding of relay SL', conductor 273, alternate contact 272 of the relay IR, conductorl 275- to ground at normal" contact 276 of the release control relay/y RY,

and the circuit of rotary relay RR' being traced from battery through the winding of the relay RR', conductor 273 to groundv at 4n'ormalcontact 276 of the relay RY.l The operator having actuatedher. key GSK to Aclpse alternate lcontact`115 immediately restores it to its normal position, and upon the first restoration `of .the .ke GSK its alternate Contact 115 is returne to normal to .interrupt the energizing circuit of the relay IR of the switch SS and the opening y of )its p alternate contact 272 of relay IR 'opens the energizing circuit'4 of rotary re. 'lay RR and the slow-acting relay SL'. Re-

lay RR'de-'energizes, but relay SL', due .to

its slow to release construction, holds its alternate -contact 277 momentarily closed to establish an energizing circuit for (the rotary magnet 4RMs of the supervising switchr SS, traced from battery through the winding of the magnet RMa, lconductor 278, normal contact'27 9, of the .relay RR' to ground at tirez-momentarily closed .alternate contact invaso@ uponV energization steps 283 and 284. of the supervising switch SS into engagement with the first set of contacts 285, 286, 287 and 288, which lead to the first connecting circuit CC which comprises tinder switch FS and connector switch CS, which were used in establishingthe connection between 'the calling subscriber at the substation A andthe called subscriber at the substation B, as before described.

Assuming that the called subscriber at the substation B to which the calling subscriber at the substation A haslbeen connected by the operator through switches'F S and CS and the operators answering equipment as before described in detail, has not as yet answered, the instant the wipers 281, 282, 283 and 284 engage the ycontacts 285,286,287 and 288, which lead to the connecting circuit just described, an energizing circuit isl established for the tonecontrol` relay TO associated with the supervising switch SS, traced from battery through the winding of the relay TO, conductor 28,9, wiper 282, contact 286, conductor l290 to of the off-normal contacts ON of the conductor switch CS whose wipers 159, 160 and 161 are in engagement with the contacts 162, 163 and 164 thatlead to the called subscribers substation B who has not as yet Relay TO upon energization clos/es its alternate contact 291 closing an energizing circuit for the tone connectlng relay TRE 'traced' from battery through the winding of the relay TRE, conductor 292, alternate contact 291 of the relay TO to ground at -alternate contact 293 of ,the off-normal con-1 tacts ON3 which lcontacts have assumed their alternate position upon the first step of the switch wipers of the lsupervising' switch SS oft' normal. The relay TRE upon energization opens its normal contacts 294 and 295 to disconnect thevspecial tone and over conductors 311 and 330 to conduc-`- T. The operators set O is connected to conductors 271 and 443 through alternate contacts 294 and 295 of relay TRE through wipers 283 and 284, contacts'287 and 288 tors 331 CS which and 331,01 the connector switch now places the operator in dire:t

connection with the. calling and called lines.I

The operator not receiving -any ,toneindicates to her that the finder switch FS and the connector switch CS are in use, and due to the fact thatthe operators set O is connected to the connecting cord conductors, she may now challenge the connection, and assuming that the calling subscriber at the substation A has not as yet received a response from the called subscriber at the substatiouB, the subscriber at the substation A in response to the challenge of the operthe wipers 281, 282, l

the medium of ground at alternate contact 247 y establish an energizing ator, tells the operator that the called party las not as yet answered. This being the case, the operator now actuates the ringing key RK of her supervising control circuit OE, andthe closing of alternate contact 99 of the actuated ringing key RK connects ground from alternate contact 99 of the key RK through normal key CRK, conduc'toll 97, normal contact 94 of the relay BG of the answering switch AS, conductor 443, through the winding of the relay RY of supervising switch SS, to battery. The relay RY upon energization closes its alternate contact 296, establishing an energization circuit from ground at normal contact 297, of the relay IR, conductor 298, alternate contact 296 of the relay RY, conductor 299, through alternate contact 300, of relay TRE, conductor 301, wiper 281, contact 285, conductors 302 and 147, 'alternate contact 148, of the relay RCO, ofthe connector switch CS, conductor 215 to battery through the winding of relay RCC ofthe conductor switch CS, and as the ringing frequency selection circuit FR has been set up as \before described, the relay RCC in energizing over this circuit again connects ringing generator G2 through alternate contact 217 of the relay RFSZ, conductor 218, normal contact 219 of relay RF S3, conductor 220, through alternate contact 216 of the relay RCC, over the previously described ringing path which passes through the called bell at the called substation B and back to ground at alternate Contact 221 of the relay RCC. Each time the operator actuates the ringing key RK of her supervising equipment OE, relay RY of the supervising switch SS is energized to bring about the actuation of the relay RCC of the connector switch CS to bring about the application of ringing current'to the called subscribers line. After the called subscriber at the substation B has answered, and the operator listeningfi'n is aware-of the fact thatthe subscribers are now in constoresthe ringingkey RK which returns cont-act 99 to normal to open the energizing circuit of the relay RY. The operator having supervised the first connecting circuit ,now actuates her stepping key C SK again to close alternate contact 115'to again circuit for the -relay IR to again bring about the energization of contact 98 of the A versational circuit, the operator now re the relay RR', and the slow-acting relay SL',

and the key upon restoration again op'ens the energizing circuits of the relays IR and RR toagainoperate the rotary magnet RM3 of the supervisory switch which inagf net steps the wipers 281, 282, 283'and 284 into engagement with the second set of contacts 285, 286, 287 and 288 which lead to the second connecting circuit.k

Assuming that the calling subscriber at and 284 ofthe supervising switch -engagement with= the first set of contacts circuit is established for' either the finder` switch FS or the connector switch CS, and Athe switches willl thus remain in their advanced position.

Assuming that the finder switch FS and the connector switch CS are in this condition, andthat the operator has actuated her key GSK to step the wipers 281,282,283 SS into 285, 286, 287 and 288 which lead to' the connecting circuit CC, comprising the switches FS and CS. that were used in es'. tablishing the connection between the calling subscriber fat the substation A and the called subscriber at thel substation B, the

operator not receivingl a tone as previously described, challenges the connection, and receiving no response is aware of the fao); that conversation between the calling subscriber at the substation A and the called subscriber at the substation B has terminated, but that they have failed to release the switches FS and CS. This being thecase, theoperator r now actuates the connecting circuit release 'key CRK of the supervising equipment OE,

` and theclosing of alternate contact 117 vof thev relayl CBK connects ground from said .alternate vcontact. 117, over conductor 118, Y through normal contact 93 of the relay BG',

of theanswering switch 'AS over yconductors 271 and 270 to battery through the winding'of the relay IR. The closing of alternate' contact 98-of thekey CRK con-- over: conductor 97, through norneets ground 94 of the relay BGr, conductor RY, and the relays IR and RY are energized; the closing of alternate contact` 297 `of relay IR and alternate contact` 305 of relay RY establishesan energizing ciry cuit for the connecting-circuit release relay sizing i vto'r310, conductor v ductor 311,

,Y ground through CCR, traced from'batt'ery through the winding of the relay CCR, alternate contact 305 f of relay 'RY, the conductor .306 to ground 'at alternatev Contact 297 of thejrelay IR. The rela 'CCR upon energization .closes its alternate contact 307, establishing an' ener'- circuit for the connector switch release relay 265, vtraced from battery toalternate contact y307 ofthe relayCCR, conduc- 271, alternate contact 294 of relay TRE,- wiper 283, contact 287, conoonductor 312, through the 'the repeating coil RCto winding 313 of y the winding. of the cona meen@ nector switch lrelease relay 265; rThe, relay 265 upon energization closes its alternate transmit disoonnectcurrent to. restore`the finder switch FS and connector switch CS,

and, assuming further that the operator.

actuates her stepping key'CSK to step the wipers 281, etc., into engagement with the `first set of contacts 285, etc., which lead to the connecting circuit that was used by the calling and called subscribers, and having assumed that the switches havel been restored, now when the wiper 282 engages contact l286 the said Contact will be free from ground due to the fact that the connector switch CS has restored, and therefore, alternate contact 247 of theoff-normal contacts ON of the connector switch CS are open as the off-normal contacts ON` have assumed their normal position when the said switch CS restores, and therefore, vno energizing circuitv is established for the relay TO of the supervisingswitch Relay TO remaining normal, its alternate contact291 remains open, and therefore, relay TRE remains at normal. `The tone TI is therefore connected through nor-- free, 5 o SS'into engagement with the next set of contacts. e

If the supervisory switch wipers 281, etc.,

are left in engagement with 4the contacts 285,-

lead to the connecting vcircuit that the switches FS and QS, and the substation A initietc., which comprises v subscriber at the calling and shev immediately steps the switch.4

ates a call,-the finder switch FS will select the calling line.` The instantthe selecting operation of the yswitch FS has bee'ncompleted, the answering switch AS will start its selectingoperation, as previously described, to select the nder switch'.y FS.-

lWhen the switchAS. hasperformed its selecting operation the operator answers the call, and the instant the operator starts 'to dial, the relay TI will energize as befpre described, andthe closing of its alternate contact 142 will establish anv energizing oiry cuit for the'release relay RR3 of the supervising switch SS, 'traced from battery,

through the winding of relayRR3, conduci tor 340, normal contact 341 of relay RY,

conductor 342, normal contact 300 of relayv TRE, conductor 301, wiper 281, contact`285,

` alternate contact 345 of off-normal contacts Withdrawal of the vcontact 345 of off-normal contacts ONS f rotary magnet RM ONS, and the 4closing of alternate contact 346 closes a circuit for release magnet RES from ground through alternate contact 346 to battery, through the winding of magnet RES; magnet RES energizing causes the retaining pawl of the switch SS and permits the wipers 281, etc., to restore, and the restoration of olf-normal contacts ON3 andthe opening of alternate opens the circuit of relay RRS, which relay in turn opens the circuit of magnet RES.

Should the wipers 281, etc., of the supervising switch SS be in engagement with aset of contacts 285,7etc., which lead to a con-l necting circuit that is in use, or has been in use, and is not as yet released, thevrelays TRE and TO will be energized as before described, and should the subscriber at substation A initiate a call, the finder switch FS will select the calling line, as before described, and bring about the operation(y of the relay AN of the finder switch FS. The closure of alternate contact 50 of relay AN will establish an energizing circuit for the release relay RRS of the supervising switch SS, traced from battery through relay RRS, conductor 340, normal contact 341, conductor 342. alternate contact 57 of relay TRE, conductor 59 to ground at alternate contact 50 of relay AN of the finder switch FS. Re-

lay RRS of switch SS will energize to close'vf a circuit for release magnet RES to release the switch SS, as previously described. Relays TO and TRE will de-energize, and the closing of normal contact 57 of relay TRE vwill connect ground from alternate contact 50 of relay AN of the finder switch FS over conductor 56 to battery through the of the answering switch AS to start the operation of the switch AS to select the finder switch FS and connect the operatorto the calling line.

From the foregoing description it may be seen that the supervising switch SS will alwaysv be restored when in an oli-normah position and a call is initiated, so that in case the switch SS is engaging a busy connection, the instant a call is initiated on one of the lines ot the group with whlch the o supervising switch is associated, the switch is' immediately restored'to open the circuit of relav TRE to permit thenormal contact 57 to close` so as to close the initial energizing circuit for 'the rotary magnetRM of the answering switch AS, so as to permit the switch AS to instantly connect the operrelease relay RRS and 117 of 'key LK, CSK, RK and ators setto the calling line. lIt this were not the case, should the operator be super- Vising connections when a cally is initiated,

ing circuit steps the wipers 281, etc., of the switch SS from one set of contacts 285, etc.,

to the next, and-having assumed that there are seven connecting circuits when the operator steps the wipers into engagement with the last connecting circuit, an eighth step of the Iswitclrwipers will place the switch wiper 281 into engagement with the last contact which'is ground, and this ground Will establish ,anenergizing circuit of the release .relay RRS of the switch SS; and the lease magnet RES -to release the switch SS, as before described. y

Assuming now that the calling` subscriber at the substation A initiates a call, 'the finder in turn operates the reswitch FS will be actuated to step its wipers into engagement with the contacts of the calling line followed `immediately by the operation of the answering switch AS to step its wipers into engagement with the contacts leading to the actuated finder switch FS and to signal the operator thatA a call is awaiting her attention, all of which has already been described. The operator having connected her set O to the connecting circuit nowfinquires the wants of the callingsubscriber at substation A. Assuming that the subscriber at substation A wishes to converse with a party on his own line, the operator requests the calling subscriber to replace his receiver. ator now actuates the calling switch release key CSW of her operators answering equipment OA, and vthe closing of alternate con- .'tact 112 of theskey CSW establishes an The oper- IUI energizing circuit-for the relay TI of the answering switch AS, traced from battery -210 at alternate contact 112 of key CSW,

conductor 113, normal contacts 114, 115, 116 the keys LK, GSK, RK and CRK of the operators supervisory equipment OE, conductor 118, alternate contact 93 of relay BG of the answering switch AS, conductors 119 and 120 to round through the winding of relay TI.' The closing of alternate contact 103 of the key CSW establishes an energizing circuit for relay of the answering switch AS traced from ground at alternate contact 103, conductor 102, normal contacts 101, 100, 99 and 98 of CRK, conductor 97, alternate contact 94 of relay BG', conductors 96 and 95 to battery through the winding of relay SE. Relays TI and SE of the answering switch AS now operate andestablish an energizing circuit forl the connector switch release relay 265 of the connecting circuit CC,traced from battery 210 at alternate contact112 of the key CSW, conductorV 113, normal contacts 114, 115, 116 and -117, conductor 118, alternate contact 93 of relay BG of answering switch AS, conductor 119, conductor 360, alternate contact 361 of relay TI, conductor 362, alternate Contact 363 of relay SE, conductor 364, normal contact 124 of relay 125, conductor 12.6,wiper 62, contact 66, conductor 127, conductor 312,

through the vwlnding 313 of .the 'repeating coil RC to ground through the-winding of relay 265.

Relay 265 upon energization closes its alternate contact 266, establishing an energizing circuit for the relay REC of the finder switch FS, traced 'from battery through fits lower winding, conductor 243 4 to ground at alternate contact 266 of relay 265. Relay'REC upon energization opens its normal contact 43 to open the energizing circuit of relay lBGr,v and the relay BG restoring, its normal contact 21 is closed to establish an energizing circuit'forthe release magnet RE; which magnet u-pon energization. withdraws the retaining pawl and. permits the finder switch wipers M11, 12,'13

and 14 to restore to normal; oE-normal oo nu tacts ON are also restored to open the circuit of relay SW. When the operatorie? the switch CS and frequency selector circuitl FR is the same as previously described, as, is also the release Aof the answering switch' AS when the operator has iinisheddialing and the release of the connector switch isthe same after conversation has terminated and the subscribers haveftransmitted a discon# neet signal is also the samed4 as previously f described.

The circuits thus )far have lbeen described, in connection with party line harmonic ringsv ing, but with a singleline wherethe subscriber is equipped with straight' line ringing and is the called party he may be connected to in the way as described in detail, and to signal the 'party on the line, the operator will actuate hei` calling device CD -to dial Vthe iirst frequency and then actuateher ring- The operator also dials for ing key to signal `the subscriber in the way.

already described in detail` The subscriber atthe substation A? may initiate a call `as before described, and the operation of the-apparatus is thesame as previously described so vas* to connectthe operators set Q at the centralized control board at the main exchange with' the calling line. Now should the,l calling subscriber justk desire informationA only, the operator gives this information and then operatesthe calling switch release key CSW to bring about the restoration of the finderl switch key FS, and the restoration of the listening the LK brings 1 about the l,restoration o answering switch AS, all of which was de-y scribed in detail, and a furtherv description Iis not thought necessary.

'Assuming now that a subscribervv atthe'` g substation A wishes to make a'to'll call, he proceeds to initiate the calllin the regular way, as before described, vto signal the operator at the centralized control board at the main-exchange, and gives the operator thc number of the party wanted. The operator at the main exchange requests the subscriber to replace his receiver and establishes the connection withrthe called. subscriber in the usual way, and then insertsa calling plug into the trunk ja'ck'TJ.4 This insertion of' the plug into the trunk jack TJ establishesv anenergizing -circuit for the cut-oii relay CO2. The cut-off .relay CO2' uponenergizaf tion closes its alternate Contact 380 establishng an energizing circuit for the impulse relay IM of the trunk selector switch TCS," 1 traced from battery thro-ugh the winding f I ofthe relay conductor 381, through windings 382 and 383 of the alternate cur- Lrent relay ALR, through the-windings c andA l of repeating coil RC', vwindings e and f of repeating coil RC2, conductor 384, alter-v nate contact 380of the relay CO2, conductor i 385 to the normal contact-38,6 of the dialing key DK', through the winding ofthe relay 387 to ground. The openingof normal con` tact 388 of relay 387 prevents the premature lighting ofthe disconnect lampDL. The

relay IM upon -energization closes its alternate"contact 389 establishing an energizing circuit Ifor the relay` SL2-and the relay RR2 ,-l

traced from ground atalternate contact 389,

conductor, 390 to battery through the-wind-v I ings of the'relays SL2 andfrelay RRzL" The relay SL2 upon energization closes its alternate contact 391, establishing `ari 'e ne1',f: ;i;zing circuit for the relay 392 4'tracedf"fron1,batteij7 through theupper winding of thel relay contact 391 of relay SLL. The operator 'at 392,l conductor 393 to ground at 4alternate i l tliecentralized control board at the main exchange now actuates the"`dialing key DK,'3

and assuming that the callnumber. of the calling subscriber A at the exchange M who initiated. the toll call is 15, the operator ac- 

